Engine/drivetrain Selection for the 818

[BrandonDrums]

If the EJ engine series is 180lbs for a longblock setup I would be impressed. From my research that isn't at all the case. Like I said, I may sound biased with my 4g63 comments, but I simply am doing preliminary research and it appears that the EJ engine series is surprisingly heavy for being all aluminum, and on a platform where every single pound should count, it seems non-ideal. I will do a bit of searching on this board specifically.

To be sure we're talking about the same thing. It's about 180 or so for just the engine, no intake, exhaust accessories, oil pan etc. Just Heads+block and internals. Having JUST sold my EJ207 3 weeks ago I can confirm that the engine is pretty light.

Further to prove my point, here's the webstore page for a built Cosworth EJ257 (the 2.5) http://www.flatironstuning.com/p-190...ssemblies.aspx

Note the weight they list on the page: 160 lbs.

The 5mt transmission is about 135 bare http://www.clubwrx.net/forums/transm...on-weight.html

The only confirmation I have found for that is shipping weights people have posted.

Assuming the Ej207 weighs 180, the total weight not including accessories is 315. Depending on what you include as engine+transmission weight the number can vary from 360lbs up to near 500 lbs.

I guess the more traditional assessment for what a WRX engine includes in being part of the engine assembly are the accessories, intake, oil pan+oil, headers, exhaust manifold turbo and intercooler along with the longblock and transmission is probably more like 400-450 lbs.

Still pretty light. But again, the rationale is not just weight but to optimize cost/performance+availability. I'm sure there are lighter engines and transmissions out there but not in the same quantity with the same aftermarket support and interchangeability. Using Subaru stuff just makes sense for a donor-car based kit intended for high volume sales.

And even if you disagree, it's pretty much set in stone that this car will use Subaru stuff only, at least in the beginning.

So I'm with many of the other guys, I just don't think it would make too much sense to spend time shoehorning another engine in the car to save weight. The idea that the Subaru stuff is heavy seems to be pretty inaccurate. No offense.

[16g-95gsx]

After weighing the few EJ components that I did, I am starting to believe your 180lb figure. At this point I wish I had simply started a thread asking for EJ engine weights as there is so little information available online. If the longblock weighs in at only 180lbs, give or take a bit, then I agree, there is likely little reason to switch to anything else.

40lbs for both heads, 20lbs for the crank, 5lbs for the rods. That adds up to only 65lbs, for what would be basically a longblock minus pistons, the block itself (aluminum), cams, valve covers, and an oil pan. Granted there are other small components added in there, but I definately see all of it weighing in closer to the 180lb mark than the original 380lb mark that I found online. The 130lb mark for the trans can also be immediately reduced due to the 2wd configuration.

Not bad at all.

[Jmcd]

I just tore down an ej20/trans.

the center diff/rear output combo is heavy! maybe 25 pounds or so

I will throw all of this stuff on a bathroom scale and get a better idea of what the whole thing weighs, sometime this week.

I think some components may be heavier because of the non-inline configuration, but nowhere near an iron block.

[PhyrraM]

Use your body as ballast. In general, bathroom scalse are not very accurate under 50 pounds or so. Weight yourself holding the part, and then again without it. Subtract the difference. It should be more accurate and easier than propping oddly shaped items on the scale.

[crobin4]

Use your body as ballast. In general, bathroom scalse are not very accurate under 50 pounds or so. Weight yourself holding the part, and then again without it. Subtract the difference. It should be more accurate and easier than propping oddly shaped items on the scale.

+1 Thats how I weigh stuff. Seems to well

[Jmcd]

Posted weights in new post, comparing these to what a k20 weighs (same ballpark, IMO): http://www.midlana.com/Diaries/Old%2.../2009June_Dec/ I think you are going to be hard pressed to justify any common aluminum i4, much less an iron one in the name of lighter weight, but for being different and ingenuous-go for it!

[16g-95gsx]

Just as an FWIW adding up the weights of the individual components of the iron block 4g63 the weight comes to around 189lbs without manifolds, this includes all internals, timing components, oil pan, etc. Of course there is an error that is generated from weighing each and every single part individually, but it gives a very close estimate. Just thought it was interesting to note since you would naturally expect an aluminum block to weigh far far less. In the end I suppose there is a lot of extra aluminum mass that must be used just as reinforcement, and with the iron block itself weighing in at around 85lbs, there is likely only but so much weight loss that is generated from using an aluminum counterpart when that is taken into account.

Something else that is interesting is that an Evo 3 16g with oil lines and water lines weighs in around 9.8lbs. Thats not bad at all for a turbo that is as cheap as it is (500 bucks or less most of the time), and yet has been proven to over 400awhp. If I recall the stock WRX turbo was around 13.Xlbs. On a EJ25 it would prove to be one hell of a torquey setup as 2.0L's typically see 20psi by 3000rpm assuming a full weight (3200lb).

[bbjones121]

Just thought it was interesting to note since you would naturally expect an aluminum block to weigh far far less. In the end I suppose there is a lot of extra aluminum mass that must be used just as reinforcement...

That is great to know. Looks like it might just be a made up rumor that the mitsubishi block is more bulletproof than the Subaru. So if the Subaru block is designed to be as strong as an iron block by adding more reinforcement structure, than it has the bigger advantage since it has a way lower cg over the mitsubishi.

[16g-95gsx]

Not sure what you're saying about a strength rumor, I was talking about iron naturally being a stronger metal than aluminum and therefore all designs being equal there would need to be more aluminum added in to make it strong enough. Similar concept to why aluminum driveshafts are larger diameters than steel. In the end the weights are very similar, and a far cry from the 380lbs that I originally thought of for the EJ. As far as the CG comment though, remember that 150 or the 180lbs of the 4g63 is located entirely in the shortblock, so I really don't think there is that much of a CG difference. I would say that the overall heigh/space requirements are going to be different for sure with EJ's being far wider and deeper with their transmissions.

[BrandonDrums]

That is great to know. Looks like it might just be a made up rumor that the mitsubishi block is more bulletproof than the Subaru. So if the Subaru block is designed to be as strong as an iron block by adding more reinforcement structure, than it has the bigger advantage since it has a way lower cg over the mitsubishi.

From what I've heard, it's not exactly a rumor but it is misleading. Subaru's do have a higher failure rate than Mitsubishi's at high HP numbers but not because of the block material or really even the block itself. The Evo engine has a more ideal bore/stroke ratio being in a vertical inline configuration. The 2.5L subaru engine is flat and because there's only so much room in the engine bay, EJ engines are rather stubby and are limited on how much stroke you can run to up displacement numbers. This isn't the case with a 2.0L wrx engine but it has other issues with oiling which can be fixed with a better oil pump.

To get the displacement on the 2.5 Subaru had to max out bore and stroke on a short block which results in an "over square" engine. They should have decreased stroke and put larger pistons in the engine but that would result in a very top-end power band.

The pistons will fail in a Subaru 2.5L more often than any failure in an Evo engine with the same numbers stock for stock. Either it's because of the oversquare engine and weak pistons or there are just more guys with subarus out there and it's a "tragedy of the commons" where more Subarus fall into the hands of guys who just over boost and under-tune their cars because they don't care.

However, the gray area is that additional HP on a Subaru engine is harder to get because of the location of the turbo and and less than ideal header/manifold flow. On an Evo, you can run lower boost and make higher numbers because of a more efficient manifold given an equal sized turbo (not to mention the evo has a front mount IC with very little piping). If you just run equal length headers, have an appropriate turbo and a quality tune I imagine the actual rate of engine failure on a Subaru wrx/sti vs. Evo would be the same if not less and the power output potential would be rather close.

So it's not really the engine in my opinion that causes Subaru's to get the bad rap for the most part. It's just the configuration of things that puts EJ motors through more stress to get the power output.

[bbjones121]

That is great info. Thanks. So it means that the subaru power plant in the 818 might not have the configuration restrictions the led to some of the limitations it faced when previously compared to the 4g63.

[16g-95gsx]

I dont see these cars running imense power levels anyway. I've seen plenty of 600awhp stock longblock evo's and DSMs to know the engines are fully capable of tremendous power in factory form, but ultimately none of that will be usable on the 818 while keeping with the spirit of a drivable car. I think weight and size restrictions are really the goal here.

[BrandonDrums]

That is great info. Thanks. So it means that the subaru power plant in the 818 might not have the configuration restrictions the led to some of the limitations it faced when previously compared to the 4g63.

Pretty much what I'm thinking. What's more important is that if you're smart enough to build a whole car, your going to be smart enough to just mainatin the car to begin with.

Good tune, good oil, good owner...these engines will last